/*
 * Copyright (c) 2014 pkzd/1.0, 颜文泽(robin)
 * All rights reserved.
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *     1 Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     2 Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include	"fs.h"
#include	<fcntl.h>
#include	<stdio.h>
#include	<errno.h>
#include	<string.h>
#include	<stdlib.h>

static int link(char *device, char *dest, char *source);

int
main(int argc, char *argv[])
{
	if(argc < 4){
		fprintf(stderr, "Usage: ./link device dest source\n");
		exit(1);
	}
	return link(argv[1], argv[2], argv[3]);
}

static int
link(char *device, char *dest, char *source)
{
	int fd;
	struct filsys spb;

	if((fd = open(device, O_RDWR)) == -1){
		fprintf(stderr, "Error: cannot open device %s: %s\n", device, strerror(errno));
		return -1;
	}
	if(bread(fd, NRSVSCT, &spb, 1)){
		close(fd);
		fprintf(stderr, "Error: cannot read superblock of %s\n", device);
		return -1;
	}
	if(spb.s_magic != FS_MAGIC){
		close(fd);
		fprintf(stderr, "Error: unknow file system of %s\n", device);
		return -1;
	}
	if(mc_link(fd, &spb, dest, source)){
		close(fd);
		fprintf(stderr, "Error: link %s %s fault\n", dest, source);
		return -1;
	}
	return close(fd);
}
